<template>
  <div class="container">
    <div class="point"></div>
    <div class="point"></div>
    <div class="point"></div>
    <div class="point"></div>
    <div class="point"></div>
  </div>
</template>

<script>
export default {
  name: 'Loading'
}
</script>

<style lang="less" scoped>
.container {
  display: flex;
  justify-content: center;
  align-items: center;
  width: 100%;
  height: 100%;
  position: absolute;
  top: 0;
  .point {
    width: 2em;
    height: 2em;
    border-radius: 50%; /* 实现圆形 */
    background: #fff;
    margin: 1em;
    user-select: none;
    position: relative;
  }
  .point::before {
    position: absolute;
    content: '';
    width: 100%;
    height: 100%;
    background: inherit; /* 从父元素继承背景颜色 */
    border-radius: inherit; /* 从父元素继承圆角 */
    animation: wave 2.2s ease-out infinite;
    /* 对before元素定义动画，完成时间2s, 采用ease-out过渡，重复循环 */
    @keyframes wave {
      50%,
      70% {
        transform: scale(2.5);
      }
      80%,
      100% {
        opacity: 0;
      }
    }
  }
  /* 设置背景颜色,自行选取五个颜色即可 */
  .point:nth-child(1) {
    background: #7ef9ff;
  }
  .point:nth-child(2) {
    background: #89cff0;
  }
  .point:nth-child(3) {
    background: #4682b4;
  }
  .point:nth-child(4) {
    background: #0f52ba;
  }
  .point:nth-child(5) {
    background: #000080;
  }
  /*
  * 现在动画都是同时出现的，而我们需要的是一种逐渐出现的效果
  * 所以需要对每个元素的动画加一个延迟
  * 最后一个与第一个之间的间隔太短
  * 所以需要把整体的动画时间延长一下
  */
  .point:nth-child(1)::before {
    animation-delay: 0s; /* 第一个不需要延迟 */
  }
  .point:nth-child(2)::before {
    animation-delay: 0.2s; /* 依次延迟0.2s */
  }
  .point:nth-child(3)::before {
    animation-delay: 0.4s;
  }
  .point:nth-child(4)::before {
    animation-delay: 0.6s;
  }
  .point:nth-child(5)::before {
    animation-delay: 0.8s;
  }
}
</style>
